For that I would be looking for a dead leg on the water pipe
You may notice when you run a hot tap, said pin is slow to operate and also slow to release when tap closed
Gas112 knows things about this boiler even Baxi might not know.
Baxi Combi 80e...is this normal operation?
- Thread starter daKlone
- Start date
You may notice when you run a hot tap, said pin is slow to operate and also slow to release when tap closed
Gas112 knows things about this boiler even Baxi might not know.
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A passive dead leg is that of a “leg of pipe” that is no longer in use, thus dead. An active dead leg is that of a longer than necessary run of pipe still in use.
I replaced the venturi and diverter valve diaphragm with no problems, switched it back on...and now it won't fire up at all. 
It's flashing "Flame Fault" and "Safety Thermostat" now.
Safety thermostat is not tripped (i.e. the contact is closed) and the wire from the PCB to the safety thermostat is buzzes out. Tried linking-out the terminals on the PCB just in case, but no change.
Wire between the PCB and the igniter also buzzes out but I can't see any attempt to fire it. Is this is locked-out because of the safety thermostat error?
It's flashing "Flame Fault" and "Safety Thermostat" now.
Safety thermostat is not tripped (i.e. the contact is closed) and the wire from the PCB to the safety thermostat is buzzes out. Tried linking-out the terminals on the PCB just in case, but no change.
Wire between the PCB and the igniter also buzzes out but I can't see any attempt to fire it. Is this is locked-out because of the safety thermostat error?
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You have got water on the pcb . turn power off take cover off pcb and dry with a hair dryerI replaced the venturi and diverter valve diaphragm with no problems, switched it back on...and now it won't fire up at all.
It's flashing "Flame Fault" and "Safety Thermostat" now.
Safety thermostat is not tripped (i.e. the contact is closed) and the wire from the PCB to the safety thermostat is buzzes out. Tried linking-out the terminals on the PCB just in case, but no change.
Wire between the PCB and the igniter also buzzes out but I can't see any attempt to fire it. Is this is locked-out because of the safety thermostat error?
Yeah, that's what I thought initially. I've taken the PCB out and it's not wet at all. I will give it a try though, just in case there's some water under a component anywhere.
I don't suppose anyone has a circuit diagram for this PCB do they?
I don't suppose anyone has a circuit diagram for this PCB do they?
It hadn't, no. But it did look old (probably the original) and the spring was a bit corroded, so I thought "why not"...at least that's one thing ruled out.
Plus there's not much point in asking for advice and then ignoring it, is there
Safety stat normally closed would seem to be correct but this seems to contradict it?.I replaced the venturi and diverter valve diaphragm with no problems, switched it back on...and now it won't fire up at all.
It's flashing "Flame Fault" and "Safety Thermostat" now.
Safety thermostat is not tripped (i.e. the contact is closed) and the wire from the PCB to the safety thermostat is buzzes out. Tried linking-out the terminals on the PCB just in case, but no change.
Wire between the PCB and the igniter also buzzes out but I can't see any attempt to fire it. Is this is locked-out because of the safety thermostat error?
Well..I'll..be..dipped!
Left the PCB for a while and then ran the hairdryer over it for a few minutes. Didn't see any water running out, but blow me if it didn't pop back into life when I put it back in.
The venturi/diaphragm seems to have helped enormously. I can run the downstairs cold full on and still have hot upstairs now.
There is still a strange initial condition, if the hot is already running upstairs and I start the cold downstairs, the hot goes off for a few seconds then comes back on. Plus the hot still comes on for a few seconds when I turn the cold off.
But as far as the initial problem goes, I'll call it solved.
Out of interest, I had a closer look at my old venturi and it looks like the "seat" was ever-so-slightly out of shape. Maybe that was the problem?
Thank you so much to everyone who contributed, especially Gas112 and Johntheo5.
Now, how do I go about figuring out where my "dead leg" is??
Left the PCB for a while and then ran the hairdryer over it for a few minutes. Didn't see any water running out, but blow me if it didn't pop back into life when I put it back in.
The venturi/diaphragm seems to have helped enormously. I can run the downstairs cold full on and still have hot upstairs now.
There is still a strange initial condition, if the hot is already running upstairs and I start the cold downstairs, the hot goes off for a few seconds then comes back on. Plus the hot still comes on for a few seconds when I turn the cold off.
But as far as the initial problem goes, I'll call it solved.
Out of interest, I had a closer look at my old venturi and it looks like the "seat" was ever-so-slightly out of shape. Maybe that was the problem?
Thank you so much to everyone who contributed, especially Gas112 and Johntheo5.
Now, how do I go about figuring out where my "dead leg" is??
Dead legs are normally pipework from an old HW cylinder that have been capped off , but really need to be cut at source rather than termination, you might not have one , usual symptom is run a hot tap till boiler fires, close tap if the boiler doesnt shut down immediately then you have a dead leg
Glad you've sorted it.Well..I'll..be..dipped!
Left the PCB for a while and then ran the hairdryer over it for a few minutes. Didn't see any water running out, but blow me if it didn't pop back into life when I put it back in.
The venturi/diaphragm seems to have helped enormously. I can run the downstairs cold full on and still have hot upstairs now.
There is still a strange initial condition, if the hot is already running upstairs and I start the cold downstairs, the hot goes off for a few seconds then comes back on. Plus the hot still comes on for a few seconds when I turn the cold off.
But as far as the initial problem goes, I'll call it solved.
Out of interest, I had a closer look at my old venturi and it looks like the "seat" was ever-so-slightly out of shape. Maybe that was the problem?
Thank you so much to everyone who contributed, especially Gas112 and Johntheo5.
Now, how do I go about figuring out where my "dead leg" is??
I would assume a dead leg problem would be caused if it contained air and will act as a mini E.vessel?
It would be interesting to see how low you can reduce the HW flowrate before it stops running hot.
Another query I've never seen answered is how far the DHW temperature has to rise above its setpoint before the burner cuts out, ie if the DHW setpoint is set to say 45C does the burner then trip when/if the temperature rises to 50C if the flowrate is reduced.
Funny you should say that, as in my loft there is a HW cylinder that is not connected to anything, so it seems to me that it is highly likely that the problem is just as you describe.
Is there any way to easily identify the culprit pipe? Is it likely to be the only "capped off" pipe up there?
Yes it will be capped off, if you find a capped off pipe crack the joint if compression , till water comes out, just like bleeding a radiator, then close it again, if you get air then water , that is the dead leg
According to the manual, the minimum working flow rate for DHW is 2.5 l/m, but I will give it a test.
I'll try to check the temperature control but obviously it's tricky to measure water temperature accurately. I would have hoped that it would work properly no matter the flow rate!
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